Process of producing dyed lustrous printed pattern effects using acidcuring resins and free leuco bases of vat dyes



Patented Apr. 15, 1952 PROCESS OF PRODUCING DYED LUSTROUS PRINTED PATTERN EFFECTS USING ACID- CURING. RESINS AND FREE LEUCO BASES OF VAT DYES George Alan Billingsley, Jr., and William P. Hall, Wilmington, Del., assignors to Joseph Bancroft & Sons 00., Wilmington, DeL, a corporation of Delaware No Drawing. Application April 9, 1948,

Serial No. 20,114

9 Claims.

This invention relates to. dyed durable lustrous printed, pattern effects for cellulose textile fabrics.

It has. been known how to produce clear, undyed (lustrous) pattern effects by printing a pattern with, a clear (containing no dyestufl") paste embodying thermo-setting resin-forming materials'which become water insoluble when heated. The thus printed fabric is then passed through a heated calender, such as a friction calender, onkwhich the resin is wholly or partially polymerized. In the latter case, the fabric is then passed through an oven to complete the polymerization.

It hasv also been known how to introduce naphthol dyes into a lustrous (and other mechanical methods) pattern, by adding the naphthol base to the unprinted cloth and then to print with a resin-printing gum mixture containing the naphthol salt. This method, although a valuable method, has the drawback of limitation of the number of durable colors obtainable on a practical scale since a given naphthol base treated cloth can only produce a few colors (sometimes only one) of good durability. Besides the naphthol range of colors are quite limited, being primarily valuable in producing red, yellow, and orange colors.

Heretoiore, it has been impossible to incorporate pigments in the printing paste and obtain a commercially practical process. This is due to the fact that when the moist printed pattern is passed through the mechanical finishing equipment, the pigmented printed pattern will mark-ofi on the hot bowls of the calenders which again will transfer the color to the cloth resulting in mark-01f. In the case of a mechanical machine such as a friction calender which operates at high temperature, this difiiculty becomes so serious after a few yards have been run that the calender actually becomes a printing machine.

The primary object of the present invention is to provide a process whereby vat dyes may be incorporated in the resinous printing paste and sharp, distinct, colored, lustrous mechanical finished patterns may be obtained having excel lent light and wash fastness and without smearing and mark-oil? of the pattern on the unprinted portion of the cloth.

It is especially valuable to be able to use a vat type of dye since this type allows a complete and full range of colors of a high degree of durability to light and washing, and exceptionally good and durable results are obtained with, the better grades of anthraquinone and thio-indigo types which are recommended for this process.

These particular dyes" come on the market in pigment form, i. e., they are in particle form, each particle containing thousands of dye molecules. In this form the dyestufl has no aflinity for the cellulose fibers and if printed upon the fabric, will mark-01f in the glazer and bleed and wash oif during subsequent washing.

To obtain the desired results, we proceed as follows:

The above vat dye or dyes are first treated in an alkaline solution containing a reducing agent, usually caustic soda and sodium hydrosulfite which will reduce the dyestuff" into what is called the leuco form underwhich conditions the dyestuff is obtained in the solution in the molecular or semi-molecular form as the sodium salt of the leuco base of the dyestuff. Dispersing agents such as- Blancol (sodium naphthalene sulfonate-formaldehyde) may also be added to aid the dispersion.

This.- alkaline solution is then carefully neutralized with an acid material preferably formic or acetic acids, until the solution is about neutral or slightly acid. Under these conditions, primarily the free leuco base of the dyestuif is obtained which, although it has less affinity for cellulose than the sodium leuco base of the dyestuff, still has a greater aflinity for the cellulose fiber and penetrates more readily than the large size pigment particles of the dyestuif as supplied.

The solution containing the leuco base is now mixed into the printing paste containing the usual type of printing gum or mixtures of printing gums such as, for example, starch, converted starch, gum tragacanth, karaya gum, locust bean gum, kelgin gums, methyl cellulose polymerized styrene gum, and acrylate gum. Any well known printing gum may be used provided it does not undesirably alter the state of the dyestuif nor interfere with the setting of the resinous material used.

Theprinting paste also contains the thermosetting resin forming ingredients which may be, for example, melamine-formaldehyde, phenolformaldehyde, urea-formaldehyde, dicyandiamide-formaldehyde, urea-glyoxal, and mixtures of melamine-formaldehyde, and urea-formaldehyde.

It is possible to have the thermo-setting resin serve as the printing gum by using, for example, polyvinyl alcohol-formaldehyde, methyl celluloseglyoxal, or starch-formaldehyde thermo-sctting materials. These products while serving as the resin forming material also have enough viscosity in solution to serve as the printing gum. Usually, under these conditions, a stiffer print is obtained and this is somewhat desirable.

If the printing paste is sufficiently acid, the use of a catalyst may be dispensed with, but usually it is found advantageous to add a catalyst to speed the setting of the thermo-setting materials. The usual type of catalysts such as, for example, diammonium phosphate, ammonium 'thiocyanate, di-monoethanolamine phosphate, ammonium sulfate, and di-propanolamine phosphate, may be employed. Catalysts should preferably not be used which would precipitate the dyestuif.

Similar printing pastes as the ones described above may be prepared using the leuco ester type of vat dyes sold on the market under the commercial names of Algosol and Indigosol. Since these leuco ester compounds of the vat dyestuff form molecular dispersions when added to water, it is possible to add these directly to the printing gum containing the thermosetting resin catalyst and lubricant together with an acid such as lactic, acetic, and sulphuric, and a mild oxidizing agent such as sodium nitrite; these latter serving to change the leuco ester dyestuff into a molecular or semi-molecular dispersion of the vat dyestuff during the processing which is identical with the procedure already described for the regular type of vat dyestuff.

The printing paste may also contain a lubricant to prevent the sticking and chewing of the cloth when passing through the mechanical equipment. This addition becomes necessary when large printed patterns are glazed as these would not go through the glazer without some lubrication. Sulfonated vegetable, petroleum, and animal oil may be used but care should be taken that these products do not flocculate or coagulate the leuco base vat dye dispersion when added to the printing paste as this will be detrimental. We prefer to use such products as polymerized ethylene oxide (Carbowaxes), lecithin, fatty chain modified melamine resin products (Aerotex Softener H), or emulsion of waxes or oil such as Japan wax, carnauba wax, and castor oil.

Lubricants of a permanent character which have a tendency to remain in the print after the final washing may also be used; these will act as softeners in the finished fabric and may also impart water resistance which is sometimes desirable when the fabric is subsequently to be overdyed as will be further explained. Among durable lubricants we may mention cation-active softeners, such as, for example, Triton K-GO (tetra alkyl quaternary ammonium chloride), Amonyx T (trialkylbenzyl ammonium chloride), stearamidomethylpyridinium chloride, and stearyloxymethylpyridinium chloride. The last two products will also impart water resistance to the finished printed pattern.

When the printing paste or pastes has or have been prepared, the fabric is printed in a customary manner, the number of printing rolls employed corresponding to the number of different colors in the pattern. The printing may also be done by means of the system known as screen printing instead of on one of the regular types of printing machines.

After printing, the cloth is carefully dried until the printed portion of the fabric Preferably contains from 5% to 15% moisture by weight of the fabric above that of the normal moisture content of the fabric. After the cloth has been dried, it may be advantageously cooled by passing it either through a cooling chamber or over cooling cans.

In the case of friction calender finish, the dried fabric is now passed through the friction calender, usually about three times. In the friction calender which exerts high pressure and friction on the fabric at elevated temperatures, the fabric is physically deformed so that a smooth, high-polished product is obtained. This glossy effect is produced over the entire fabric, but will only have a durable character where the fabric was printed, and during the subsequent washing after curing, the fibers and yarns in the unprinted portion will loosen or swell and destroy the mechanical finish, giving a dull eifect. 0n the other hand, the printed portion containing the thermo-setting material will, after curing, be durable to the subsequent washing treatment and the mechanical finish will remain, resulting in a two-tone effect between the printed and the unprinted portion, showing a high glossy print against a durable background.

If the heated bowls on the friction calender are operated between 300 F. and 400 F., polymerization will occur on the calender, and if a sufiicient number of runs are given, the polymerization of the resinous material may actually be completed thereon. In case the polymerization is not completed on the calender, it is advantageous to give the fabric a short cure at elevated temperature to complete the setting. We prefer to operate the calender at high pressure (40 ton total pressure) and with a friction ratio of from about 1 /2 to 1 to about 3 to 1. The heated steel bowl has the higher surface speed.

Other calenders imparting mechanical finishes to textile fabrics may also be used. In the case of the chase and flat nip calenders, we prefer to operate at a temperature of from approximately 200 F. to 300 F. on heated bowls. In the case of the schreiner and embossing calenders, we prefer to operate between the temperatures of approximately 200 F. to 400 F.

The curing of the resin depends to some extent upon the previous treatment the cloth has received. As stated above, it is possible to completely cure the fabric by multiple runs on a calender operating at high temperatures. When operating at the lower temperatures using two or perhaps three runs, it is preferable to cure the fabric in an oven at a temperature ranging from 250 F. to 400 F., and a period of time rangin from 10 minutes to 1 minute. In the case of the chaser and the fiat nip calender, we prefer to cure the fabric in an oven at a temperature ranging from about 250 F. to about 400 F., for a period of time ranging from about 15 minutes to about 2 minutes.

We prefer to give the fabric a final washing treatment to remove soluble materials and any superficial mechanical finish present on the fabric and also, as previously stated, to remove the mechanical finish which has-been applied to: the unprinted part ofthe fabric. This washing is preferably done in the open width. by a light soaping treatment in a dilute soapv solution followed by thorough washing in hot water. The fabric is finally squeezed and dried.

Thatthe pattern does not mark off even when using a hot friction calender, we attribute to. the fact that the d'yestuifis. present inthe printing paste primarily in a molecular or semi-molecular form rather than in large pigment particle form, so that when printed and partly dried, the. dyestuif penetrates and adheres to the fabric. and stays there during the calendering rather than sticking on the hot bowl and then marking off on the cloth. Thus, if the same dyestufi as sold in pigment form is added to the same printing paste, printed; dried, and calendered, it will. be found to smear and mark-on" within a few yards.

It is impossible. to develop the vat dyestufi after printing and before calenderingsince such treatment would smear the pattern. The usual steam aging method of developing vat prints cannot be used prior to calendering since the steam aging sets up the resinous material, resulting in a non-durable mechanical finish. To develop the dyestufi after calendering and curing is also impractical since the strong chemical treatments at elevated temperatures necessary to develop the dyes will either destroy or seriously reduce the mechanical finish.

If desired, the cured fabric may be run through an oxidizing solution to insure complete conversion of the leuco dyestuff to. the. keto. or insoluble. form. For this. purpose, for example, hydrogen peroxide, sodium perborate, and potassium dichromate may be used. This step, however, is not necessary since ithas. been found that the contact with the air during printing, drying, and curing, has for all practical purposes already converted the dyestuif to the keto or insoluble form.

Instead of using caustic soda. and sodium. hydrosulphite to reduce and disperse the vat. dyestufi, other methods well known in the art may be used. For example, the caustic soda may be substituted by potassium hydroxide, trisodium phosphate, soda ash, triethanolamine, and other strong alkalies. The hydrosulphite maybe substituted by sodium sulfoxylate formaldehyde, sodium ibisulphi-te, sodium hydrosulphite formaldehyde, and others. For all practical purposes, sodium liydrosulphite and caustic soda are used in proportions which vary according to dyestulf but which are well known in the art.

The percentage of thermo-setting material in the printing may be varied between wide limits, depending upon the degree of stillnessv desired in the printed. portion. The latter may vary between a softflexible print. approaching the unprinted part of the cloth. in hand to a firm stifi pattern imposed upon a soft flexible background of unprinted cloth. In general, we. operate. between 6% thermosetting materialin the printin gum to 25% by weight of the paste.

The percentage of dyestuir'may also be varied. It is, of course, rather difiicult: to give a: lower limit since. the printing; paste may be applied: in the tinted form, in. which case. only a very small quantity of dyestuif is used, say .l% by weight of the paste. The upper limit on the percentage of dyestuif varies, depending upon the ease with which a dyestuif will. mark. ofi during the mechanical processing and. also upon many other factors, such as percentage of moisture in the printybefore the; mechanical: treatmenitis; applied. type of gum, lubricant, and other ingredients. of theprinting paste, quantity of paste deposited by the printing" machine, and heat, pressure and friction applied during the mechanical processing Commercial operations have indicated that in general we may operate-with. a dyestuff percentage; of..1,2% by weight in the printing; using a hot friction glazer which: is the most. difficult machine. to operate as far as mark-off and smearing are concerned.

Where the patterns. represent approximately 80% coverage, no difficulty is encountered in passing the fabric through the friction calender. In. the friction calender, however, if the coverage is substantially less, than 80%, then it is desirable, in order to prevent chewing of the fabric, to size the fabric before printing with a sizing producing. substantially the. same coefiicient of friction as the printed areas after printing. The sizing solution should contain a small percentage of the lubricants mentioned previously, usually about 10% by weight, and may in addition also contain a small percentage of some stiffening agent such as, for example, dextrin, casein, glucose, and starch.

The fabric after curing or after washing and drying, may be subjected to further auxiliary textile treatments to produce new and novel effects. For example, a sheer lawn having the lustrous colored patterns applied may be subjected to cellulose swelling treatments such such as, for example, treatments with cuprammonium solutions and caustic sodium zincate solutions to produce organdy effects, the final results. being alustrous colored pattern on a sheer organdy fabric.

In a similar manner, it is possible to overdye the finished cloth and obtain the lustrous colored patterns on a dyed background.

In all such. after treatments, it is essential that they be so chosen that. they do not detrimentally affect the lustrous colored pattern already applied. This danger may be somewhat reduced by using as a lubricant materials which have durable water repellent properties such as, for example, stearamidomethylpyridinium chloride and stearyloxymethylpyridinium chloride.

Example I The printing paste was made by first preparing the molecular or the very fine dispersion of the vat" dye-stuff. The following formula was used to prepare this dispersion:

Parts by weight Ponsol Jade Green Dbl/Paste (C. I. 1101) 766 Caustic soda, 75 deg. T. W.- 460 Sodium hydrosulphite 259 Blancol (sodium naphthalene disulphonateformaldehyde) 307 Acetic acid, 510 Water 7698 The Blancol was dissolved in one-half of the total amount. of. water and the. color then added. The whole mixture was mixed very thoroughly. To this was then added first the caustic soda and then sodium hydrosulphite with agitation. and' Aerotex M-3 (methyl-methylol melamine) 2080 Ammonium thiocyanate 208 Carbowax 1500 (polymerized ethylene oxide) 416 Water 3136 The vat dyed dispersion previously prepared was first added to the Supertex Gum T-125 and then carefully mixed. The Aerotex M43 resin was dissolved in water and added with thorough agitation. The Carbowax 1500 and the ammonium thiocyanate were put in solution and added with careful mixing. After that, the paste was strained and a smooth, uniform paste of good printing property was obtained.

A 40", 48/48, 3.50, cotton fabric which had previously been purified through the regular bleaching process was printed by passing it through a regular textile printing machine followed by careful drying, so that approximately 10% moisture above the normal moisture remained in the printed portion of the cloth. The cloth was then taken to a conventional friction calender having a friction ratio of 3:1, a total pressure of 40 tons, and a temperature of the upper steel bowl of approximately 350 F. The cloth was given three runs through this calender and during this procedure, no mark-off, smearing, or staining of the unprinted portion of the cloth took place.

tests and light tests conducted on this fabric showed excellent durability both as far as color and finish were concerned.

Example If A dispersion of reduced vat dyestuff was prepared as described in Example I, except that Ponsol Violet BN Paste (C. I. 1163) was used as the dyestuff.

The printing paste used in'this case had the following composition:

Parts by weight Reduced dispersion of Violet BN Paste as prepared above 2000 Supertex T-125 2000 Aerotex Cream 450 (urea-formaldehyde resin, 50%) 833 Rhonite 414 (urea-formaldehyde resin,

40%) 1667 Ammonium thiocyanate 200 Sapamine KW (tri-methyl ammonium methyl sulfate of monostearylmethaphenylene diamine) 400 Water 2900 This paste was prepared by adding the reduced dispersion of the vat acid to the Supertex Gum with good mechanical stirring. The Aerotex 450, Rhonite 414, Sapamine KW, and the ammonium thiocyanate were dissolved in water and added with thorough mixing to the Supertex Gum containing the reduced acid. The paste was then strained in the usual manner, producing smooth, homogeneous paste of good printing properties.

A 40", 46/40, 3.50, spun rayon fabric was presized by padding it through a solution containing dextrine and /2% sulphonated tallow by weight and then framing to width.

The cloth so prepared was printed in the regular printing machine, using the conventional methods of printing and using the printing pastes described above. The cloth after printing was carefully dried until approximately 10% of residual moisture above the normal moisture remained in the printed portions of the fabric. This fabric was then passed once through a 5-bowl heavyweight chasing calender, using a temperature of 300 F. on the heated bowls and a total pressure of 30 tons on the machine.

After chasing the fabric was cured in a loop type aging chamber for 5 minutes at 310 F.

The cloth was then washed through a warm solution containing a small quantity of detergent and alkaline material, followed by a thorough washing in warm water.

The fabric was then extracted and frame dried.

The resulting cloth had a mellow, deep-seated lustrous, colored pattern imposed upon a dull white background of unprinted cloth. This eifect was durable to drycleaning, soaping, treatments, and light.

Example III Dispersion of the leuco base was prepared as previously described, using the following formulation:

Parts by weight Indanthrene Red Violet RHA Paste Fine (0. I. 1212) 766 Potassium hydroxidesolid 109 Sodium hydrosulphite 259 Blancol 307 Formic acid, 88% 157 Water 8402 Reduction is carried out in the same manner as described for Example I.

A printing paste having the following composition was prepared:

Parts by weight Indanthrene Red Violet RHA Paste Fine reduced vat solution as prepared above 2080 Locust bean gum-5% 2780 Aerotex M-3 750 Diammonium phosphate 624 Aerotex Softener H 416 Water 3350 The vat acid is added to the locust bean gum and thoroughly mixed. The Aerotex M-3, diammonium phosphate, and Aerotex Softener H are dissolved and added under constant agitation, after which'the paste is strained.

' Printing and processing are handled the same as for ExampleI.

Example IV A four-color lustrous printed pattern on a dull dyed fabric was obtained.

Example V A printing paste of the following composition was made up:

Parts by weight Algosol Green lBW Paste (C. I. 1101) 75 Carbowax 1500 1000 Lactic acid (85%) 100 Ammonium thiocyanate 120 Aerotex M-3 2000 Sodium nitrite 150 Supertex T-125 4000 Water 2400 Color was pasted with small amount of water, added to Supertex T125, and mixed thoroughly. Sodium nitrite, Aerotex M-3, and Carbowax 1500, put into solution and added in order. Finally, the lactic acid (85%) and ammonium thiocyanate in water solution were added and the total mixture was strained. Printing and processing was carried out as described in Example I.

We claim:

1. The process of producing durable colored lustrous pat-tern efiects on cellulose textile fabrics which consists in printing the fabric with the desired pattern with an aqueous printing paste containing a vat dyestuff in free leuco base form and thermosetting acid-curing resin forming materials, said paste containing a sufficient quantity of acidic material to ensure the existence of an acid environment during the heating hereinafter mentioned, drying the printed fabric to from 5% to moisture by weight of the fabric above natural moisture content, passing the dried fabric through a pressure mechanical finishing machine, heating to polymerize the resin forming materials to insoluble form, and washing the fabric.

2. The process of claim 1 in which the dyestuff is an anthraquinone.

3. An aqueous printing paste for use in producing durable mechanical colored lustrous pattern effects on cellulose textile fabrics, which tern efiects on cellulose textile fabrics, which consists essentially of Water, printing gum, vat dyestuff in free leuco base form, thermosetting acid-curing resin-forming materials, an acidic catalyst, and a softener.

6. The process of claim 1 in which the dyestuif is a thio-indigo.

7. A printing paste according .to claim 3 in which the dyestuff is a thio-indigo.

8. The printing paste of claim 5 in which a textile lubricant is employed in lieu of a softener.

9. A printing paste according to claim 5 in which a textile lubricant is employed in addition to a textile softener.

GEORGE ALAN BILLINGSLEY, JR. WILLIAM P. HALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,909,221 Paquin May 16, 1933 2,123,153 Rivat July 5, 1938 2,169,546 Widmer Aug. 15, 1939 2,267,609 Kern Dec. 23, 1941 OTHER REFERENCES Textile Manufacturer for March 1949, page 132.

Textile Manufacturer for December 1946, page 647.

Application and Properties of Vat Dyes, Calco Tech. Bull. #802, June 1948, American Cyanamid Co., Bound Brook, N. J page 19. 

1. THE PROCESS OF PRODUCING DURABLE COLORED LUSTROUS PATTERN EFFECTS ON CELLULOSE TEXTILE FABRICS WHICH CONSISTS IN PRINTING THE FABRIC WITH THE DESIRED PATTERN WITH AN AQUEOUS PRINTING PASTE CONTAINING A VAT DYESTUFF IN FREE LEUCO BASE FORM AND THERMOSETTING ACID-CURING RESIN FORMING MATERIALS, SAID PASTE CONTAINING A SUFFICIENT QUANTITY OF ACIDIC MATERIAL TO ENSURE THE EXISTENCE OF AN ACID ENVIRONMENT DURING THE HEATING HEREINAFTER MENTIONED, DRYING THE PRINTED FABRIC TO FROM 5% TO 15% MOISTURE BY WEIGHT OF THE FABRIC ABOVE NATURAL MOISTURE CONTENT, PASSING THE DRIED FABRIC THROUGH A PRESSURE MECHANICAL FINISHING MACHINE, HEATING TO POLYMERIZE THE RESIN FORMING MATERIALS TO INSOLUBLE FORM, AND WASHING THE FABRIC. 